The mineralization and growth of bone are processes intimately related to the composition and organization of the extracellular proteins which comprise the bone matrix. Although the homeostatic control of bone formation and resorption are well defined, the biochemical mechanisms of matrix formation, mineralization and remodeling are unknown. Morphologic and autoradiographic data suggest that the noncollagenous proteins (NCPs) and proteoglycans (PGs) are involved in bone formation and maintenance. In order to gain insight into the role of the NCPs and PGs in osteogenesis, their chemical characteristics, biosynthesis and secretion, and fate will be studied. These studies will first be directed toward the isolation and characterization of chemical amounts of NCPs and PGs using a non-degradative extraction procedure as designed for the study of dentinogenesis. Using these bone specific NCPs and PGs, antibodies will be raised in order to aid in subsequent organ culture experiments. Organ cultures will be carried out on rat calvaria and long bones in order to detail the biosynthesis, secretion and deposition of matrix NCPs and PGs.